The hippocampal region plays a prominent role in learning and memory, particularly in declarative or explicit memory expression and permanent memory consolidation. Yet, despite significant advances in characterizing aspects of memory that are dependent on the hippocampal system, we have little insight into the fundamental cognitive mechanisms, the neural coding schemes, or the cortical-hippocampal interactions that mediate declarative expression and consolidation. This project is aimed to address these issues within an animal model of declarative memory. The three general long-term objectives of this project are 5 grants: (1) Neuropsychological experiments will clarify cognitive aspects memory processing dependent on components of the hippocampal system. (2) Electrophysiological experiments will characterize the firing patterns of single neurons and neuronal ensembles of cortical and hippocampal areas in rats performing tasks that have different cognitive and memory demands, and determine whether cortical memory codings are dependent on hippocampal processing. (3) Aging studies that involve both neuropsychological assessments and electrophysiological recordings will determine what aspects of cognitive function and neural coding in the cortex and hippocampal systems are compromised in normal aging. Together these approaches will provide a broad systems-level analysis of the cortical and hippocampal contributions to declarative memory essential for daily life and compromised in several neurological disorders and normal aging. In collaborative studies the PI will pursue new research career developments, including studies on temporal coding patterns, neural ensemble recording and analyses, aging research, and neurophysiological studies on monkeys. In addition, the PI will increase his mentoring activities with postdoctoral fellows and graduate students, complete writing of graduate level, book-length survey of memory systems in the brain, and develop a program for research opportunities for undergraduates, and particularly for women at Boston University and Wellesely College. The proposed award will release the PI from substantial teaching obligations to pursue these research and other activities.